Add sensitivity analysis support for exponential distribution

[nehill197]

No description provided.

[nehill197]

To increase the sd of the exponential distribution, we need to divide the rate parameter by a factor:

x <- seq(0, 50, by = 0.01)

rate <- 2
plot(x, dexp(x, rate), type = "l")
lines(x, dexp(x, rate * 10), type = "l", col = "blue")
lines(x, dexp(x, rate / 10), type = "l", col = "red")

n <- 10000
ran <- rexp(n, rate)
sd(ran)
mean(ran)

ran_mult <- rexp(n, rate * 10)
sd(ran_mult)
mean(ran_mult)

ran_div <- rexp(n, rate / 10)
sd(ran_div)
mean(ran_div)

[nehill197]

Fix regex to have it correctly modify the form dexp(1/10)